This invention relates to exposure systems in general, and more specifically to devices which utilize light rays to expose some special surface in order to produce various effects.
A number of devices require the exposing of some special surface to light rays in order to produce various desired effects. In a photographic process, for example, a photosensitive surface is commonly used. In such cases the surface that is sensitive to radiant energy can be either film or paper. In electrophotographic processes, a photoconductive surface (one that has its electrical conductivity changed by radiant energy) is used. Such systems find application in printers which utilize a light source to electrically charge or discharge a previously blanket charged portion of a photoconductive surface, usually a drum, in a patterned manner to permit application of toner, or ink, which is then transferred eventually to a paper to create a printed document.
In prior art printer systems, a master light source, usually a large, linearly constructed laser is used. In such systems, it is necessary to deflect laser light beams by means of a rotating mirror system, or an acousto-optic crystal system in order to produce the desired pattern resulting in printed characters. Modulation (turning on and off) of the beam is accomplished by electronic circuitry external to the laser. Such systems are generally bulky and costly, and they necessarily physically separate the light source, modulation and scanning elements of the photoconductor discharge system. Another disadvantage was that the speed of operation of the existing systems was necessarily limited because of the larger size.